I can't find a relevant documentation on whether .NET Framework 3.0 (since Entlib is built on .NET 3.0) and .NET Framework 2.0 will work with SQL Server 2008 R2. According to its
System Requirements, it requires .NET Framework 3.5 SP 1 so I just assume that it will not work. Regarding with your last question, you can refer to the
Entlib 5.0 System Requirements and
Entlib 5.0 ChangeLog. Hope this helps.